Parkinsonian patients treated chronically with levodopa may develop complex fluctuations of neurological symptoms. We will monitor patients' neurological signs and plasma levodopa hourly throughout the waking hours for two days to: 1. Determine if establishing the magnitude and pattern of fluctuating symptoms and signs leads to improved control and would be a cost effective service. 2. Explore unusual patterns of response for other clues to the pharmacokinetic and pharmacodynamic properties of levodopa.